Totally disagree! I own a short .biz domain (erica.biz) and have had people mis-speak it when introducing me as "ericabiz.com"...so much so that I put in a backorder on ericabiz.com and when the previous registrant finally let it drop this year, I snagged it and 301'ed it to erica.biz.
I still love erica.biz and have no intentions of switching over to a .com, but there's no question that people assume you have a .com.
Search engines, however, don't care--my site happily gets tens of thousands of visitors per month from Google et.al. and the site ranks well for some very high-volume keywords.
I had one of the first .biz domains in 2001 and used it to run a 7-figure business. Back then, it was far less accepted than it is now. My blog is doing fine, too (and I get tons of compliments on the domain name!)
My point is, it sure didn't stop my company from getting hundreds of happy customers, some of whom paid us more than $10,000 per month.
I still love erica.biz and have no intentions of switching over to a .com, but there's no question that people assume you have a .com.
Search engines, however, don't care--my site happily gets tens of thousands of visitors per month from Google et.al. and the site ranks well for some very high-volume keywords.